The present invention relates to a printer and, more particularly, to a continuous form printer whereby a number of different forms can be simultaneously loaded in the printer and a chosen form can be selectively shuttled into position for printing.
Continuous forms have a series of sheets with evenly spaced holes along their lateral edges. The sheets are usually separated by perforated lines so that they can be conveniently detached from one another. A printer is adapted to handle such continuous forms by the use of a tractor, which typically has a pair of formhandling jaws containing sprocketed belts that can be controllably driven or rotated. The jaws are positioned to line up with the lateral edges of a form so that the holes of the form can be aligned with, and engaged by, the tractor sprockets. The form can then be transported through the tractor by rotating the sprocketed belts. A tractor can be located in a printer either before the actual printing apparatus (typically the combination of a platen and print head) such that forms are fed into the printer, or the tractor can be located after the printing apparatus so that forms are drawn through the printer. Tractors are particularly useful for handling pre-printed continuous forms because they provide for consistent and accurate positioning of each form thereby allowing matter to be printed reliably in the correct place on the forms.
Most printers accommodate only a single type of continuous form at any given time. Consequently, whenever it is desired to use a different form, the user must unload the current form from the printer and load the new one. Changing forms can be time consuming and inefficient, especially for those who regularly use several different forms.
Continuous forms also often have multiple layers or parts so that copies of the form being printed are made simultaneously. Such multiple part forms are more difficult for printers to handle, though, because they are stiffer than single layer forms and their layers can delaminate when the form is forced to curve or bend at too great an angle. Because of this, many forms makers recommend that their multiple part forms not be used with rear-fed printers, which require bending the form at approximately 90.degree. during transport to the print head. Consequently, it is desirable to provide a print path for the forms which requires as little bending as possible.
Accordingly, it is a principal object of the present invention to provide a multiple form printer where continuous forms travel in a generally straight up print path.
A related object is to provide a simple and reliable mechanism for shuttling a selected tractor and form into position for printing.
Another object is to provide a printer which allows convenient access to load and unload continuous forms into and out of the tractors.
These objects, as well as others that will become apparent upon reference to the accompanying drawings and following detailed description, are provided by a printer which includes an array of movable tractors. The tractors are movably mounted in a frame and each tractor can be operated by a main tractor rotating drive. The tractors are moved to various positions by a shuttle drive, and a guide mechanism provides a guide path whereby each respective tractor can occupy the print position. When a tractor is in the print position, the leading edge of a continuous form transported through that tractor is fed into the printer. The tractor shuttle arrangement also permits each of the different forms to travel a path so that it passes straight through the platen when that form is selectively moved into the print position.
Preferably the platen, carriage, and print head of the printer are located in a hinged upper casing which can be tilted up away from the tractor shuttle frame and apparatus to facilitate loading continuous forms into the tractors.